Method for the production of abrasive brushing elements

ABSTRACT

An abrasive brushing element such as a wire bristle, a strip or a plate having the tip and a substantial portion thereof clad with a layer of a metal such as nickel, wherein is bound a layer or more of very fine abrasive powder, such as tungsten carbide. The article is produce by crushing a material of high hardness to a very fine particle size and imparting an electrostatic charge at the surface thereof. The fine particles are then caused to electrostatically adhere at the tip and along a substantial portion of the brushing element while metal plating, preferably with nickel at least that portion of the brushing element.

O United States Patent [151 3,669,850 Draca June 13, 1972 [5 METHOD FORTHE PRODUCTION OF 2,391,206 12/1945 Van Der Pyl.... ..204/16 ABRASIVEBRUSHING ELEMENTS 2,424,140 7/1947 Beecher ..204/16 [72] Inventor: CedoDraca, 2165 Barnes Street, St. Lau- FOREIGN PATENTS OR APPLICATIONSrent, Montreal 388, Quebec, Canada 346,473 4/1931 Great Britain [22]Filed: July 18, 1969 Primary Eraminer.lohn H. Mack [21] Appl 843090Assistant Examiner-TTufariello Att0rneyRaymond A. Robic [52] U.S. C1..204/16,l17/16,117/17,

117/31, 204/15, 204/23, 204/27 [57] ABSTRACT [51] Int. Cl. ..C23b 7/00,C23b 5/48 An abrasive brushing element such as a wire bristle, a stripor [58] Field of Search ..204/16, 23, 3, 4, 15, 27; a plate having thetip and a substantial portion thereof clad 1 17/17, 26 with a layer ofametal such as nickel, wherein is bound a layer or more of very fineabrasive powder, such as tungsten car- [56] Referen e Ci d bide. Thearticle is produce by crushing a material of high hardness to a veryfine particle size and imparting an electro- UNITED STATES PATENTSstatic charge at the surface thereof. The fine particles are then causedto electrostatically adhere at the tip and along a sub- ;JggfigJE/Jlllggl Smysen ..117/17 Stamial portion of the brushing element whilemetal plating l l/ l 5 Johnstonm 17/17 preferably with nickel at leastthat portion of the brushing ele- 2,12s,907 9/1938 Benner et a1 ...11717 mm 2,297,691 10/1942 Carlson ...117/17 2,343,957 3/1944 Crompton, Jr..117/17 17 Claims, 2 Drawing Figures PATENTEDJUN 1 3 1972 QVI r/m AUXINVENTOR Cedo DRACA ATTORNEY METHOD FOR THE PRODUCTION OF ABRASIVEBRUSI-IING ELEMENTS This invention relates to a method for theproduction of abrasive brushing elements such as plates, strips andbristles used in the making of industrial brushes. More particularly,the invention relates to a bristle material presenting greater wearresistance, durability and abrasive power that hitherto used materials.

Most commonly, the bristles of industrial brushes are made of steel andparticular stainless steel, and some present protective and/orstrengthening metal coatings covering the surface of the wire, It isalso known to make bristles of superior abrasive power by settingparticles of abrasive compounds at the tips of the wires in the mannerthat diamonds are set in a diamond drill bit; such a solution wasproposed for example in U.S. Pat. No. 2,608,034. Whereas it was foundpossible to set abrasive particles of manipulable sizes at the tips ofwire bristles, the setting of similar granules elsewhere along thebristles would have been impractical as it would have necessitatedexcessive increase in the radial dimension of the wires with a resultantobjectionable degree of stifiening.

The present invention proposes a solution that permits obtaining auniform distribution of abrasive particles at and away from the tip ofeach wire without the aforementioned defects of the prior art reference.

The improved bristle of the invention consists of a metal wire, at leasta portion of which is clad with an electrodeposited layer of metalwherein is bound a layer or more of very fine abrasive powder. Coveringthe tip of the wire bristle and the fine abrasive powder, is a coatingof a metal, preferably nickel, which has been made by metal plating.

The method according to the invention therefore comprises crushing amaterial of high hardness to a particle size smaller than about 100 u,imparting an electrostatic charge at the surface of the small particlesof a material of high hardness, causing an amount of theelectrostatically charged small particles to become electrostaticallyretained at the tip and along a substantial portion of a brushingelement, and metal plating the brushing element which has smallparticles electrostatically retained thereon.

Through the preferred brushing element is a wire bristle preferably madeof steel, it is understood that the present invention can also beapplied to strips or plates or any other brushing elements used inindustrial brushes.

The material of high hardness which is crushed to a small particle size,preferably 0.5 to 100;.t, includes a carbide material. The term carbidematerial which is used throughout this disclosure and claims includessilicon carbide and preferably tungsten carbide. The commerciallyavailable product usually consists of a tungsten carbide and anickelcobalt binder; minor amounts of carbides of other refractorymetals are often present particularly those of titanium and tantalum,but less frequently those of the other refractory metals such ascolumbium, molybdenum, vanadium, chromium, zirconium and hafnium. Allsuch materials are characterized by their great hardness which is, inpart, attributable to the hardness of the particular carbide. Thepractice of the invention is facilitated by the fact that the requiredcarbide materials are generally available commercially; nevertheless, itmust be understood that the invention also contemplates the possibilityof utilizing all kinds of carbide materials.

Since only the tips of the brushing element is treated in the abovemanner, the remaining portions are usually masked by applying acommercial wax wherever suitable. The purpose of masking these portionsof the brushing element is to confine the deposit of abrasive particlesand the corresponding metal coating to a specific area which requires tobe hardened.

After having masked the brushing element, it is recommended to clean thelatter in a hot alkaline metal cleaner for a period of 2 to 3 minutes,to rinse the same thoroughly in hot water and to dry it in air beforecausing the small particles to become retained at the tip thereof.

The crushing of the material of high hardness is preferably carried outin a ball mill, the latter being capable of inducing alone electrostaticcharges at the surface of the small particles. However, the electriccharges on the small particles is imparted more successfully if anelectrostatic powder gun is used to shoot electrons in a mass of smallparticles.

It is recommended to crush the carbide material to a particle size assmall as possible, since then the same will adhere more easily, whenelectrostatically charged, to the brushing element.

In accordance with an embodiment of the invention, the electrostaticallycharged small particles are formed in a paste or slurry before beingretained at the tip of the brushing element, and this is done by addinga non-electrolyte volatile liquid, such as isopropanol to the particles.

Metal plating may be carried out by dipping the brushing element havingelectrostatic charged particles of tungsten carbide or the like at thetip thereof, in a metal plating bath and allowing the metal, preferablynickel, to coat the tip of the brushing element. It is recommended toadd a small amount of an activator to the metal bath. Preferably, thisactivator is nickel chloride which is added as an alcoholic solutioncontaining 75 milligrams NiCI, per liter of alcohol. It is also believedthat this activator helps to increase the life of the electrostaticcharge in the suspension comprising the metal plating bath. In somecases, the galvanic effect produced when metal plating could cause thesmall particles to be removed from the tip of the brushing element. Forthis reason, a small quantity of an electric current is induced in thebrushing element, and this quantity is only sufficient to retain thesmall particles at the tip of the brushing elements while preventingthem from passing into the metal plating bath.

Generally, the brushing element is gradually introduced into the platingbath while applying the above small current, and at the same timegradually raising the voltage after the entire length of the portion tobe plated has been dipped and subjected to initial plating at lowdensity.

In the drawing which illustrates the invention,

FIG. 1 is a cross-section view of the tip of a stainless steel bristletreated by the process according to the invention,

FIG. 2 is the same view of the same stainless steel bristle plated alongthe entire length thereof.

Referring to FIG. 1, it will be seen that the wire bristle 1 issurrounded at the tip and along a substantial portion thereof with alarge number of small particles of tungsten carbide 3. i

The whole is plated with nickel coating 5 and the gradually thinning outportion 7 is produced by first dipping the brushing element until itreaches the level 9 and gradually raising the bristle wire 1 to formthis portion 7. The plated wire bristle is then suddenly removed fromthe metal plating bath.

In FIG. 2, the wire bristle 1 has a nickel coating which extendssubstantially past the portion containing the small particle of tungstencarbide 3. This portion 11 serves to define more stiffness in the wirebristle.

It is recommended to carry out the plating operation by keeping the bathcold, provided the temperature is not below 60 C.

I claim:

1. A method of producing abrasive wire bristle which comprises:

a. crushing a material of high hardness to a particle size smaller thanabout t;

b. imparting an electrostatic charge at the surface of the smallparticles of hard material;

c. causing an amount of the electrostatically charged small particles tobecome electrostatically retained at the tip and along a substantialportion of said wire bristle; and

d. metal plating said wire bristle having said small particleselectrotatically retained thereon.

2. A method according to claim 1, in which said wire bristle is made ofsteel.

3. A method according to claim 1, in which said material of highhardness is a metal carbide.

4. A method according to claim 1, in which said metal carbide istungsten carbide.

5. A method according to claim 1, wherein said material having highhardness is crushed to a particle size in the range between about 0.5xto about 100A 6. A method according to claim 1, wherein said crushing iscarried out in a ball mill, which induces said electrostatic charges atthe surface of said small particles.

7. A method according to claim 1, wherein said electric charge isimparted to said small particles by an electrostatic powder gun.

8. A method according to claim 1, wherein wax is. applied to said wirebristle to mask the portions of said wire bristle where small particlesand metal plating are undesired.

9. A method according to claim 8, and comprising cleaning and dryingsaid wire bristle before causing said small particles to becomeelectrostatically retained thereon.

10. A method according to claim 1, wherein said electrostaticallycharged small particles are formed into a paste or slurry byaddingthereto a non-electrolyte volatile liquid before being retained at thetip of said wire bristle.

11. A method according to claim 1, wherein said metal plating is carriedout by dipping in a metal plating bath said wire bristle having saidsmall particles electrostatically retained thereon.

12. A method according to claim 11, wherein said metal plating bath alsocontains a small amount of an activator.

13. A method according to claim 12, wherein said activator is nickelchloride.

14. A method according to claim 10, wherein said volatile liquid isisopropyl alcohol.

15. A method according to claim 11, wherein said metal plating iscarried out while applying a small current to said wire bristle, saidcurrent only sufiicient to retain said small particles on said wirebristle, while preventing the same from passing into the metal platingbath.

16. A method according to claim 1, wherein said wire bristle is platedwith nickel, on the entire length thereof.

17. A method according to claim 15, wherein the tip of said wire bristleis gradually introduced into the plating bath, while gradually raisingthe voltage after the entire length of the portion to be plated has beendipped and subjected to initial plating at low density.

I II! I l l

2. A method according to claim 1, in which said wire bristle is made of steel.
 3. A method according to claim 1, in which said material of high hardness is a metal carbide.
 4. A method according to claim 1, in which said metal carbide is tungsten carbide.
 5. A method according to claim 1, wherein said material having high hardness is crushed to a particle size in the range between about 0.5 lambda to about 100 lambda .
 6. A method according to claim 1, wherein said crushing is carried out in a ball mill, which induces said electrostatic charges at the surface of said small particles.
 7. A method according to claim 1, wherein said electric charge is imparted to said small particles by an electrostatic powder gun.
 8. A method according to claim 1, wherein wax is applied to said wire bristle to mask the portions of said wire bristle where small particles and metal plating are undesired.
 9. A method according to claim 8, and comprising cleaning and drying said wire bristle before causing said small particles to become electrostatically retained thereon.
 10. A method according to claim 1, wherein said electrostatically charged small particles are formed into a paste or slurry by adding thereto a non-electrolyte volatile liquid before being retained at the tip of said wire bristle.
 11. A method according to claim 1, wherein said metal plating is carried out by dipping in a metal plating bath said wire bristle having said small particles electrostatically retained thereon.
 12. A method according to claim 11, wherein said metal plating bath also contains a small amount of an activator.
 13. A method according to claim 12, wherein said activator is nickel chloride.
 14. A method according to claim 10, wherein said volatile liquid is isopropyl alcohol.
 15. A method according to claim 11, wherein said metal plating is carried out while applying a small current to said wire bristle, said current only sufficient to retain said small particles on said wire bristle, while preventing the same from passing into the metal plating bath.
 16. A method according to claim 1, wherein said wire bristle is plated with nickel, on the entire length thereof.
 17. A method according to claim 15, wherein the tip of said wire bristle is gradually introduced into the plating bath, while gradually raising the voltage after the entire length of the portion to be plated has been dipped and subjected to initial plating at low density. 